Vorstedt should never have been revealed as the killer.
SPOILERS
Granted, this is not a universal opinion, but suddenly revealing Vorstedt (out of nowhere) to be the one to run Victoria Riggs off the road is an example of bad writing. I know Shane Black had a hand in the script, but I've also seen other names attached, so I don't know who's to blame. And it doesn't ruin a good movie for me, but it's certainly unnecessary.
It's obvious why they did this...they needed something to make Riggs snap and go ballistic on the bad guys. But it could've been handled a lot better than just coming up with this on the fly. All they had to do was build up the Riggs/Rika relationship a little but more, and that alone should've been enough to send Riggs over the edge and start killing people. Here was a fresh start at happiness for Riggs, and they snatch it right out from under him and kill an innocent woman.
The bad guys even proclaimed war on the police department! What more reason does Riggs need? His friends are dead!
It's the same thing that happened in Spider-Man 3. The Sandman was never even a glimmer in anyone's eye when the first movie was filmed and Ben Parker was murdered. The audience and Peter knew that Blondie killed Ben. That moment is what created Spider-Man. But wait! Peter, Blondie was just the other guy in the car. Sandman really pulled the trigger! Again, same reason. The writers are trying to come up with a reason for Spider-Man to go after The Sandman. "Well, let's see..... we could make him the murderer! All we'd need to do is refilm the crime scene but insert Thomas Haden Church, and BOOM! Now he's the killer, not Blondie!"
Things like this should never be rehashed to give motivation. Both movies had enough motivation to avoid a cheap shot like this.
-----
"Fuzzy wuzzy killer polar bears!"